Friction couplings can be used in various ways in vehicle occupant restraint systems. Examples of these are an arrangement for putting at rest for sensors, the drive of reversible belt tensioners, loop brakes, motion dampers in movable buckle extenders, rotation speed limiters in belt locking systems or the like. All friction couplings have in common here the fact that a defined prestressing of the friction element, a defined looping, angle and a particular friction factor are required. The friction moment provided by the friction coupling increases exponentially with an increasing looping angle and increasing friction value between the friction element and the component, on which the friction element engages.
Owing to the exponential course of the friction moment, the minimum friction moment transferred from the friction coupling can be adjusted comparatively simply within desired tolerances. This is more problematic with the maximum friction moment which can be transferred from the friction coupling. Deviations of the looping force of the friction moment from a nominal value upwards have a very much stronger effect on the friction moment than deviations downwards.
The object of the invention consists in further developing a friction coupling of the type initially mentioned to the effect that the friction moment transferred to a maximum from the friction coupling is limited.